Before (focus on left bottom status bar):

After:

Just to mention it, Thunderbird on Windows has it, Firefox or IE don't... not sure about this one. I tend to don't care ;).

Prefer to keep it (it's not hurting anything), but don't care.

@luke-jr: I know. It's minimal.
But have a look at the screenshot/mockup below.
I really care about margins and paddings.
The right unused margin in the status bar always poked me.

Tested ACK

prebuilt binaries for testing: https://builds.jonasschnelli.ch/pulls/5628/

Seems a bit like the UI equivalent of premature optimization. Isn't the point of a size grip to communicate that the window can be resized?

@laanwj: Right. But the grip is only visible on windows. On Linux and Mac there is a unused space to the right.

On window there are many apps where the grip is not visible but the window is also resizable.

See also:
Internet Explorer, Filer-Explorer, Terminal: nowadays most apps/windows don't have a resize handle.